Search Documents

By D. W. Butner

The blast -hole method for drilling and breaking ground is not new to the mining industry . For several years it has been used rather extensively in Canada , particularly in the gold mines , where it was first developed and where the major advances in the technique as applied to present - day mining problems have been made . At present , 40 mines in Canada and the United States are using the method in one form or another , and from all indications its use will increase in the future . In two California mines , blast -hole diamond drilling is now used for a part of or for all stoping operations , and in one of these it is used to some extent in development work . At the Mountain Copper Co.'s Hornet mine in Shasta County, about 50 percent of the pyritic sulfide ore produced is mined by the blast - hole method , and the U. S. Vanadium Corp. mines 80 percent of the ore produced at its Pine Creek tungsten mine in Inyo County by this method . At Pine Creek , long -hole drilling and blasting is used for mining pillars also , and in pre - stoping development . The blast -hole diamond - drilling method is not applicable to all types of ore bodies . A third property in California , the El Dorado Limestone Company , El Dorado County, tried the method for several months in 1943 and 1944 , but , owing to certain factors that greatly increased mining cost , the company soon returned to conventional mining methods .

Feb 1, 1948

By Qingzhu Li

The brewing industry byproduct, spent grain (SG), was evaluated for its ability to adsorb Ag(I) from aqueous solutions. Ag(I) adsorption was dependent on solution pH, contact time, adsorbent dose, initial Ag(I) concentration and temperature. The kinetic data were well described by pseudo-second-order kinetic model, indicating that chemical adsorption was the rate-controlling step. The equilibrium data followed Freundlich isotherm rather than Langmuir isotherm, suggesting heterogenity of the adsorption sites on spent grain. Ag(I) desorbed from Ag(I)-loaded spent grain was also evaluated in this study. HCl, NaOH, Na2S2O3 and ultrapure water were chosen as eluants and desorbed Ag(I)-loaded spent grain for 30min, Ag(I)-loaded spent grain desorbed in 0.1M Na2S2O3 exhibited higher elution efficiency as compared with other eluants. The results indicated that application of spent grain for adsorption and recovery of silver from aqueous solutions was feasible.

Jan 1, 2009

By Ralph M. Foecking

The disposal of the phosphate slimes produced by Florida beneficiation operations is perhaps the biggest single problem of the phosphate mining industry. This is an old problem which has not been solved and which is becoming increasingly severe. In a typical phosphate mining operation, the phosphate rock mined is initmately mixed with sand and clay, constituting what is known as matrix. During the beneficiation, the clay and other fine materials are separated usually at -150 mesh, and washed from the phosphate rock in a form of diluted slurry known as phosphate slimes. The quantity of slimes solids and their composition vary considerably with the location but usually represent from 25 to 35% of the ore mined. Because of the affinity that clays have for water, large volumes of water are required to separate the granular material in the matrix forming a dilute slime suspension (1.5 to 3% solids) of colloidal material, which settles very slowly, and thus requires immense impounding areas, which never becomes totally usable land. These ponds also contain about 25 to 35% of the total P205 values mined. The magnitude of the problem represented by the slimes can be appreciated better if we realize that there are around

Jan 1, 1971

By F. Baczek, S. S. Rocks, D. Chaiko, C. Eyzaguirre, S. Asihene, T. Walters

The majority of efforts to improve primary copper sulfide leaching have focused on solution chemistry, temperature, O2 pressure, ultra-fine grinding, the use of catalysts, etc. Historically, very few studies have focused on the solid/solution interface. A new, patent pending approach to catalyzed, copper sulfide leaching has been discovered by FLSmidth that enables manipulation of the 2-D semi-conductor properties of chalcopyrite surfaces to the benefit of higher electrochemical reactivity. Copper dissolution rates are then further accelerated by incorporating a Stirred Media Reactor (SMRt) into the process. By using minute amounts of Cu2+ to "pre-activate" chalcopyrite, leach times have been reduced from >20 hours with incomplete Cu dissolution to <2 hours with 98+% Cu dissolution at 80°C. The pre-activation process takes only minutes to complete at temperatures of 80°C or less. The total atmospheric leaching process, incorporating the pre-activation and Stirred Media Reactor is compatible with existing SX/EW processes. Results of batch leach testing are presented and possible mechanisms are discussed.

Jan 1, 2015

The Bureau of Mines has sponsored a comprehensive research program to enhance the safe, effective, and efficient use of blasting technology by the mining industry. Recent research results of the surface mine blasting program were presented at a seminar on April 25, 1987, in Chicago, IL. Many of the topics discussed at the seminar are presented in this proceedings. The new research described in these papers includes computer monitoring of rock motion, the influence of blast delay times on rock fragmentation, blasting effects on Appalachian water wells, blast vibration measurement near structures, and the reduction of accidents through improved blasting safety.

Jan 1, 1987

By A. C. Fieldner

All technical facilities of the Bureau of Mines have been geared for more efficient use and conservation of mining equipment, developing plans for safety, improving the quality of coal through better methods of preparation, studying the problems of coal storage and utilization, and extending the uses of coal5/ for the war and postwar economy. The Bureau is now analyzing all of the coal purchased by the Army and much of that required by the Navy. Work on boiler feed water was doubled over last year to meet the increased demand made by the War Department for protecting vital boiler plants in many new camps and defense plants. Progress has been made in safely storing coal to reduce dangers of spontaneous ignition to a minimum and to preserve coking power. Mixtures of oil and coal to be used as a substitute fuel have been investigated. Technical service on the conversion of plants to other fuels has been given to government agencies and private consumers. The possibilities of making motor fuel,

Jan 1, 1944

By T. Liu, C. Shi, T. Fu, M. Zhong

Water inrush in coal mines is induced by the imbalance of the groundwater flow field and the engineering geo-mechanics field. Therefore, to prevent water inrush it is important to predict the critical hydraulic pressure of water inrush in coal seam floors. This paper will investigate a method for conducting theoretical forecasting of the critical hydraulic pressure of water inrush in coal seam floors by adopting the combination method of a genetic algorithm-neural network. First, the topology structure of a neural network (NN) based on genetic algorithms (GA) will be determined and then the critical pressure of water inrush in a coal seam floor using the chosen NN will be predicted. Finally, theoretical forecasting results will be compared with actual measurement results to determine the feasibility and applicability of this method.

Jan 1, 2008

By Yunyan Wang

Diagrams of pc-pH for the complex ions concentration and pH value and -g- for activity coefficient and ionic strength ln±MnSOI4had been drew based on the thermodynamic principle of coordination chemistry and combined with Pitzer theory at 298.15K. The diagram of -g- indicated that -gincreased sharply from 0.0000 up to 1.2147 when I changed from 0.00 ln±MnSOIln4±MnSO4to 0.09; The increase of -gbecame slowly when I was more than 1.00 and less than 1.69; kept still when I ln±MnSOln4-g±MnSO4was more than 2.25 and less than 4.00. Diagrams of pc-pH illustrated that the minimum solubility of Mn(OH)2(s) increased with the increase of I, the pc increased from 6.5 to 5.5 when I increased from 0.00 to 4.00; The pH of the minimum solubility of Mn(OH)2(s) increased with the increase of I, the pH increased from 11.80 to 12.76 when I increased from 0.00 to 2.89, the pH kept still when I (I was less than 4.0) increased. There is single function relationship between the minimum solubility of Mn(OH)2(s) and relevant pH in different I.

Jan 1, 2010

By Carlos M. Fontes Vieira, Ruben J. Sanchez Rodriguez, Carlos E. Gomes Ribeiro

"The worldwide demand for ornamental stones in building construction is motivating the use of their wastes, generated during fabrication, to produce compound stones. This work has as its objective to investigate the production of an ornamental compound marble (OCM) under vacuum and compression processing of a polyester matrix composite with addition of marble waste as load and as filler. Square OCM composite plates were subjected to compression and flexural mechanical tests. Samples were analyzed to obtain the density and water absorption. The OCM composites presented properties within the expected range of an artificial stone.IntroductionMarble is a limestone, composed mainly of calcite, more or less crystallized by metamorphism that ranges from granular to compact in texture. It has a density 2.7 g/cm3 and its porosity is approximately 0.4%. The UNI 8458 standard defined marble as: ""every crystalline rock constituted mainly by minerals with a Mohs hardness equal to 3-4"". In marble production around70 - 75% of whole extract material is lost in byproducts generation [1,2].In function of large volume of residues generated, the ornamental stones industry has attracted ever more the attention of environmentalists [3].Actually the marble can be pulverized to obtain calcium carbonate for industrial applications. It is also possible to obtain a thinner powder to produce concretes [l]. Some authors study the use of stone residues in concrete mortars and ceramic bricks, getting better properties to these materials [3,4].The marble residues can be also used in engineered stones, or ''agglomerated"" stones, production. The most common engineered stones in the market consist, like a polymer concretes, in polymer matrix composites incorporating petreous components. In the formulation of the engineered stones, the particulate or granular petreous components are the result of fragmentation or trituration processes to which natural stones were submitted to [ 5]."

Jan 1, 2014

By P. J. Hancox

Heavy mineral deposits have been known from Liberia since the1950s from both river and beach placers. The heavy mineral content of beach sands ranges between 28?62% and the suite includes ilmenite, rutile, zircon and magnetite. These occur together with kyanite, sillimanite, staurolite and garnet. The average ilmenite content is 82% with minor zircon (11%), rutile (6%) and monazite (1%). The ilmenite is, however, of poor quality with haematite intergrowths and a titanium content ranging from10?42.4% (average ±25% TiO2). The amounts of rutile and zircon, while of suitable quality, have also previously been deemed too low for economic exploitation.

Jan 1, 2000

By J. Kulas, J. Weaver, K. Hagley

An assessment of potential groundwater movement beneath the tailing impoundment at the Red Dog Mine was performed, and has indicated a unique aquifer situation within sub-permafrost groundwater at the site. The aquifer was shown to be isolated from both vertical recharge and a real discharge, and is characterized as a virtually no-flow system. The permafrost resulted in a deep aquifer with high tidal efficiency, meaning that variable surface loads are easily transmitted to the fluid. The tidal efficiency has been characterized through analysis of water level fluctuations that respond to earth tides, barometric pressure loads, and loading from the pond.

Jan 1, 2002

By Michael Harris, David Mosch

The numerous small high grade gold and silver deposits of the Front Range Mineral Belt have been uneconomical because of the high costs of mill construction, transportation, and smeltering. Processing of these ores must be simple, cheap, with satisfactory recoveries, and be environmentally acceptable. Vat leach with direct electrolytic recovery satisfies these parameters. A battery of testing was conducted utilizing bottle and bucket tests. A five ton vat leach with direct electrolytic recovery gave excellent results while a five ton heap leach proved impractical due to channeling.

Jan 1, 1987

By A. C. Fieldner

The annual reports of the research and technologic investigations conducted by the Bureau of Mines on the occurrence, properties, mining preparation, and uses of coal, of which the present report is the seventh,4/ are intended to be brief summaries of progress. They are guides to the current work and publications of the Bureau but do not replace the more complete reports published by individuals and groups of workers on specific problems. The annual reports present the results of tests, often in advance of publication in other forms, but original contributions in research are reserved for initial publication by their authors. A survey of the accomplishments of the Bureau in research and technologic work on coal during the 5 year period 1935-40 has been made available in the form of a bibliography.5/ This supplements a similar bibliography on this subject that covers the first 25 years of the Bureau, 1910-35.6/

Jan 1, 1943

By C. T. Christensen

The paper gives an outline of the design, installation and performance of a series of mooring and berthing dolphins for a major ferry berth outside the port of Elsinore, Denmark. The Dolphins are large cylindrical bottle shaped and open ended steel piles vibrated into the sandy seabed. They are subsequently equipped with prefabricated fender units. Vehicle access to the ferry is via a fixed ramp and a semi-submerged linkspan. Supplementary passenger access is via a covered gangway steel bridge from an existing gangway facility to a midship door in the ferry«

Jan 1, 1989

By Fang Wu

The paper designs an extraction flow for the total recovery of nickel and cobalt and removing magnesium simultaneously from the cadthodic materials of the spent hydrogen-nickel and cadmium-nickel batteries. The separation of Co, Ni and Mg though P507 extraction .The extraction equilibrium pH is 4.5~5.0, ßNi/Co is 140~180, and ß Ni/Mg is 20~25; nickel and magnesium are scrubbed in two steps, in which the equilibrium pH of nickel and magnesium scrubbing is controlled at 5.0±0.1 and 4.4±0.1 respectively. The stepwise scrubbing technique is adopted to remove 94.5% of magnesium and to recover 99.45% of nickel and 95.35% of cobalt. During the integrated extraction and precipitation process the total recovery fraction of nickel and cobalt are 99.99% and 99.95%, and the recovery fraction of magnesium is 94.02%.The recovered NiSO4 and CoSO4 solution are enriched and crystallized.

Jan 1, 2009

By Glenn Norris, Tyler Buckingham

"Gold recovery gains in the order of one to two percent have been realized in 2009 due to changes in the operation of the grinding circuits at Barrick Gold Corporation’s Hemlo - Williams Mill. The initiative known as “split milling” involves milling low grade open pit ore in one grinding circuit and higher grade underground ore in the other grinding circuit under different conditions.The philosophy of split milling involves processing higher grade underground ore at a lower throughput rate and a finer grind while milling lower grade open pit ore at a higher throughput rate and a coarser grind. Bench scale tests showed that the recovery relationship for underground ore sources was much more grind sensitive than that of open pit ore. This relationship proved to hold in the plant. The gold recovery gain due to finer grinding of the higher grade ore is much greater than the recovery loss due to coarser grinding on the lower grade ore. Since the majority of gold is being recovered at a higher rate, this results in higher overall plant gold recovery when compared to the traditional operation philosophy of blending the ore sources.The challenges for achieving the maximum benefits of split milling were two fold; the need to increase throughput on the open pit ore milling circuit and a means of grinding finer on the underground circuit. The former was met with an increase in SAG (Semi-Autogenous Grinding) mill ball charge, a basic “drill to mill” blasting campaign and changes to the primary gyratory crusher. The latter was met with a reduced SAG mill ball charge and a higher milling density. The resulting benefits in additional gold recovered are in the order of $3-5 million per annum.INTRODUCTIONThe Williams Mill processes ore from three different ore sources, the David Bell Mine (DB), the Williams Underground Mine (WUG) and the Williams Open Pit (OP). All three ore sources are located within the Hemlo camp in Northwestern Ontario adjacent to the Trans-Canada Highway. The Williams Mill was built in the mid 1980’s at which time it was designed to process 3,000 dry metric tonnes per day through a 22’ SAG mill in series with a 16’ ball mill. In 1988 a Mill expansion doubled the mill capacity by adding a second identical grinding circuit. A photo of the current grinding circuit can be seen in Figure 1. Today the Williams Mill processes an average of 8,000 tonnes per day of which approximately 60% is from the Williams Open Pit."

Jan 1, 2010

By K. M. Kim

A site-specific blasting model has been developed for the Asarco Mission mine. The main inputs to the model are the in-situ block size (F80), the post-blast fragmentation (P80) and the intact tensile strength (To). The output from the model is the specific blast energy (ESE). Modern techniques are being used to obtain the input parameters for the site-specific blast fragmentation model. In particular, image processing software is used to obtain both the in-situ block size and the post-blast fragmentation, and the Schmidt hammer is used to obtain the tensile strength at numerous locations throughout the rock mass. An initial model was developed using five test shots in one area of the mine that contains Argillite and is relatively homogeneous. This also included calibrating Schmidt hammer readings against actual Brazilian tensile measurements. The model for Argillite will be updated as more tests are conducted, and the model will be extended to the other four primary rock types at the Asarco Mission mine.

Jan 1, 2011

By Pablo González, Rodolfo Espinosa, Jose-Luis Noyola, Sergio Cossio

"Minera Penmont, at La Herradura, is a joint venture between Industrias Peñoles, S.A. de C.V., and Newmont Mining Corporation. The mine is located in the northern Mexican state of Sonora. La Herradura consists of an open pit mine with two-stage crushing and heap leaching facility, the gold is recovered from the pregnant solution using the Merrill-Crowe process; production began in July 1998. La Herradura produces about 130,000 gold ounces per year, and treatment capacity is 22,000 tonnes/day. Ore mineralization occurs in a shear zone with quartz and native gold. Gold distribution is quite heterogeneous due to the coarse visible gold, in some coarser particles ranging from 100 to 600 microns.Sampling and assaying protocols where established during exploration and prior to starting up operations, based on nomographs developed from early heterogeneity tests. But, as the coarse gold problem became noticeable, it was necessary to develop new sampling protocols to have an acceptable relative standard deviation to control the fundamental error within ± 15%.An experimental program was developed and conducted on a selected ore block made of 195 blastholes; regular ore grade control procedures were applied to both sets of data to evaluate the difference in results between the protocol established prior to starting up operations (“existing”) and the new protocol (“leaching”). In the “existing” protocol, subsampling is done through riffle splitters, and coning and quartering. Fire assaying is used to estimate the gold content, on a 50 g sample. In the “leaching” protocol a 12,000 g sample was bottle rolled cyanide leached, and the leach residue was assayed on a 50 g sample using fire assaying, and a weighted average total gold content was calculated. Currently, a new alternative method is being evaluated, where sub-sampling is done using rotary splitters, and fire assay on a 50 g sample; in this “rotary sampling” protocol and for comparison purposes, gold assays were also repeated using the “leaching” protocol.Test results were compared in three groups < 0.30 g/t (below cut-off), 0.30 to 0.8 g/t, and >0.8 g/t. Overall. Results show that the protocol established prior to starting up operations underestimates the gold assays. Detailed technical results, alternative options, and their implications are discussed in the paper."

Jan 1, 2003

By V. Bush, T. G. Killingsworth, E. P. Ruffel

Effective and sustained corporate energy management programs are becoming a necessity for energy users as electricity deregulation laws are enacted on a state-by-state basis across the country and environmental regulations pertaining to emissions become more prevalent. The “Total Energy Asset Management” (TEAM) approach has been developed to assist energy end users with the development and implementation of corporate energy management programs designed to reduce energy risks and increase energy cost savings. This paper highlights the ways in which this approach can be applied to the mining industry while minimizing initial program implementation costs and increasing potential program benefits. Nearly the entire mining industry has become very focused on identifying opportunities to reduce costs per unit of yield. The industry as a whole has increasingly faced pricing pressures in large part due to the effects of global competition. The result of international marketplace participation and the emergence of higher efficiency recovery techniques have resulted in flat or even decreased prices for mining products. Thus, opportunities to reduce costs are actually opportunities to gain a competitive edge over similar mining operations. Due to the energy-intensive nature of many mining operations, the costs associated with energy are often a substantial percentage of operating costs. Therefore, it becomes very important to develop the corporate mentality that energy is an asset whose use should be optimized globally. In addition to the cost benefits of the TEAM approach, other benefits may occur such as reductions in facility greenhouse gas emissions.

Jan 1, 2002

By N. I. Basuki, E. T. C. Spooner

"The Bongara area, northern Peru, contains Zn-Pb mineralization with characteristics typical of Mississippi Valley-type (MVT) systems. The northwest-southeast-trending late Triassic-Jurassic car¬bonate host rocks of the Pucará Group were locally replaced by early (D1) and late (D2) dolomite. Fluid inclusion microthermometric data from dolomite and sphalerite are typical of MVT ore fluids (78° to 187°C; ~15-23 wt.% CaCl2 equivalent), and do not show apparent covariation between temperature and salinity.Homogenization temperature data from D1 and D2 dolomite show a decrease from northern (mean Th = 138°C) to central (mean Th = 126°C) to southern areas (mean Th = 102°C), suggesting fluid flow from north to south. Assuming a geothermal gradient of ~30°C/km and an average surface temperature of ~20°C, the lower temperature limits might approximate the ambient host-rock temperatures, whereas the upper temperature limits may represent minimum temperatures of a deeper aquifer, probably at a maximum depth of ~6000 m. The lower temperature limits are also similar to the estimated temperatures if dolomitization and mineralization took place in the Late Cretaceous at ~2000-3000 m depth, probably during the formation of the Peruvian fold and thrust belt near the present day Peru-Ecuador border.Fluid inclusion data show that the fluids in each studied location had relatively uniform temperatures and salinities during dolomitization and mineralization. A significant salinity drop and a slight temperature decrease are observed during late calcite precipitation, suggesting mixing of brines with dilute, cooler fluids."

Jan 1, 2009